Steady-state solution of Fig. 2 in 3D as seen from above. The yellow cylinder denotes the light cylinder and the pale undulating surface is the equatorial current sheet. Only open magnetic field lines just inside the rim of the northern polar cap are plotted. The Y-point in this solution lies significantly inside the light cylinder. The clear azimuthal break of open field lines is evident very close to the Y-point where B_p → 0 and B_ϕ ≠ 0.